High temperature generating high intensity burners



Dec. 12, 1967 F. J. LYCZKO 3,357,471

HIGH TEMPERATURE GENERATING HIGH iNTENSITY BURNERS Filed March 29, 1965 5 Sheets-Sheet 1 FIGZ I 5/ INVENTOR FEL/X J. LYCZA O ATTORNEY Dec. 12, 1967 F. J. LYCZKO 3,357,471

HIGH TEMPERATURE GENERATING HIGH INTENSITY BURNERS Filed March 29, 1965 3 Sheets-Sheet 2 INVENTOR FZ/X JI ZVC'Z/(O ATTORNEY Dec. 12, 1967 F. J. LYCZKO HIGH TEMPERAT RE GENERATING HIGH INTENSITY BURNERS 5 Sheets-Sheet 3 Filed March 29, 1965 INVENTOR [fl/X J. (VC'ZKO I W J ATTORNEY United States Patent HIGH TEMPERATURE GENERATING HIGH INTENSITY BURNERS Felix I. Lyczlro, lioxford, Mass., assignor to Thermo Electron Engineering Eorporation, Waltham, Mass, a corporation of Delaware Filed Mar. 29, 1965, Ser. No. 446,472 4 Claims. (Cl. 1587.5)

This application is a continuation-in-part of my copending application Ser. No. 201,980 filed June 12, 1962, now Patent No. 3,243,612, which discloses and claims a thermionic engine application of a burner embodying this invention.

This invention relates to high temperature generating high intensity burners.

The burners of this invention are adapted for burning fossil fuels, such as coal, vegetable matter, hydrocarbons in liquid or gaseous state, including natural gas, etc. Hence they find wide application wherever such fuels are available for generating heat to power thermionic engines or convertors requiring relatively high temperatures of the order of 2400" F. (1330 C.) in the case of current cesium vapor diodes, steam boilers to produce superheated steam at temperatures of the order of 600800 F. for driving a steam engine and wherever high temperatures are required.

It is a principal orject of the present invention to provide a high temperature generating high intensity burner which operates efiiciently with fossil fuels, with good fuel economy, which is safe, compact, durable and with its associated parts, including the material heated by the combustion products formed of a mass and size such that the units containing the burner are conveniently portable.

It is another object of this invention to provide a procedure of generating relatively high temperatures by burning fuel, which process can be carried out with a minimum of extraneous heat losses, good fuel economy, is safe and adaptable to generating high temperatures wherever required and fuel and an oxygen containing gas, such for example as air, are available.

Other objects and advantages of this invetnion will be apparent from the following detailed description thereof.

In accordance with the process aspects of this invention, a well insulated general tubular longitudinally extending region is provided comprising a combustion chamber zone having at the exit end thereof a heat transfer member of good heat conductivity in heat exchange relation with the material to be heated. The latter can be the emitter of a thermionic engine, the walls defining a water jacket and steam chamber of a steam boiler, or other surface to be heated. Fuel and preheated oxygen containing gas, preferably air, are supplied to the combustion chamber, generating products of combustion, which flow through the combutsion chamber, to which preheated secondary air is supplied, if necessary, to insure complete combustion. The products of combustion thus formed, while at or near the1r maximum temperature are jetted in a multiplicity of closely spaced jets onto the surface to be heated so that the jets impinge over substantially this entire surface. The jetting of the combustion products in this manner insures maximum heat transfer because it prevents the formation of a boundary layer of relatively stagnant gases (or removes such layer if formed before the jet impingement thereon) along the surface of the heat transfer member, which layer would interfere with good heat transfer. The products of combustion flow from the heat transfer member within the well insulated region in heat exchange relation with the oxygen containing gas to preheat the oxygen containing gas and is exhausted from the burner at or near the fuel inlet end of the combustion chamber.

ice

In accordance with the apparatus aspects of the present invention, the burner comprises a longitudinally elongated tubular combustion chamber shell, fuel and preheated oxygen containing gas inlets at one end of this shell and a heat transfer surface at the opposite end. An orifice plate is positioned close to this heat transfer surface. Combustion products flow through the orifices in this plate to form closely spaced jets of combustion products impinging on substantially the entire area of the heat transfer surface. A passageway leads from this orifice plate towards the fuel inlet end of the combustion chamber. The combustion products which had been jetted onto the heat transfer surface are exhausted through this passageway. These combustion products flow in heat exchange relation with the oxygen containing gas supporting combustion of the fuel or fluid fuel when the latter is used to preheat the oxygen containing gas and, if desired, also the fluid fuel. The entire assembly is well insulated to minimize loss of heat.

The above noted and other objects and advantages of the present invention will be apparent from the following specification taken in connection with the accompanymg drawings which show, for purposes of exemplification, preferred embodiments of this invention to which, however, the invention is not confined.

In the drawings:

FIGURE 1 is a perspective view of a diode embodying this invention;

FIGURE 2 is a section passing through the longitudinal axis of the diode taken in a plane passing through line 2--2 on FIGURE 1;

FIGURE 3 is a vertical section at right angles to the section of FIGURE 2 and taken in a plane passing through line 3-3 on FIGURE 2;

FIGURE 4 is a perspective view showing a preferred arrangement of batlles or vanes through which the fuel and oxygen containing gas, e.g., air, is admitted to the combustion chamber to obtain good mixing of these media;

FIGURE 5 is a vertical section taken in a plane passing through line 55 on FIGURE 2;

FIGURE 6 is a vertical section taken in a plane passing through line 6-6 on FIGURE 2;

FIGURE 7 is a vertical section of a modified construction involving a plurality of diodes arranged radially relative to one combustion chamber;

Referring to FIGURES l and 2 of the drawings, the construction shown involves a housing 10 having therein an emitter 11, a collector 12 separated from the emitter by space 13 to which, if desired, cesium or other ionizable gas which negates space charge can be supplied from a reservoir, not shown. While in the embodiment shown the housing is cylindrical, any desired shape can be employed. Contiguous to the emitter is a combustion chamber 14 having a centrally disposed exhaust tube 15 through which the products of combustion are discharged in heat exchange relation with the annular chamber 16 to which air or other oxygen gas is supplied to support combustion of fuel, e.g., natural gas, introduced through fluid fuel lines 17. The outer wall of hot shell 18 of combustion chamber 14 cooperates with a spaced wall, the so-called cold wall, 19 to define an annular space 21 maintained under vacuum, i.e., connected to a vacuum pump or evacuated and then sealed. In the case of a cesium diode the vacuum is of the order of mm. of mercury. For other ionizable vapors the vacuum will depend on the vapor pressure of the vapor used. Where no ionizable vapor is used, a vacuum as high as obtainable is employed, the higher the vacuum the better. A vacuum of at least 10 or 10' mm. of mercury should be employed.

It will be noted from FIGURE 2 that wall 19 is provided with a relatively thick layer of heat insulation 20,

which minimizes or completely prevents loss of heat. Thus the annular chamber 16 and the combustion chamber 14 are effectively insulated against loss of heat through the cylindrical wall 18 by the evacuated space 21 and through the concentric wall 19 by the insulation 20.

The space 13 between the emitter 11 and collector 12 communicates with annular evacuated space 21 and is thus maintained under vacuum. Emitter 11 is supported by hot shell 18 made of a suitable material of good heat conducting, high temperatureand oxidation-resistant material shaped as shown in FIGURE 1 in the form of a cylinder. Emitter 11 is secured to base 22 of shell 18 as by brazing. The ends of the hot shell 18 are secured to a supporting end closure disc 23 as by welding or other suitable gas-tight joint.

Emitter 11 in its entirety or the surface opposite the collector 12 is of a suitable electron-emissive material. Suitable materials are rhenium, osmium, tantalum, molybdenum, iridium, tungsten and niobium; other electronemissive materials can, of course, be used and this invention is not confined to those mentioned. The surface of collector 12 opposite the emitter can be of the same or a different electron-emissive material than that of the emitter and is chosen to give maximum electron flow from the emitter to the collector. Hot shell 18 which supports the emitter 11 can be of tantalum coated with an aluminum tin alloy to protect it against oxidation, or molybdenum protected with a suitable heatand oxidationresistant coating such as a molybdenum disilicide coating or tungsten having a tungsten disilicide coating. Any high temperature-resistant material which is also good heat conductnig and resistant to oxidation under conditions prevailing in the combustion chamber 14 can be used for the hot shell 18.

The collector 12 may be of copper or of other good heat conducting material having a surface opposite the emitter surface of electron-emissive material such as those mentioned for the emitter. An all copper collector can be used, in which case the cooling fins 24 can be integral with the collector. Cooling fins 24 can be of any relatively light, good thermal conducting material such as aluminum or copper. Desirably they are brazed or otherwise secured to the collector 12 spaced approximately onefourth inch apart in the form of plates as shown in FIG- URES 1 and 2 in the drawing which provide good heat exchange between the collector and the atmosphere, and thus maintain the collector at the desired temperature differential relative to the temperature of the emitter. In the case of the diode, such as that disclosed, for example, in the Hatsopoulos et al. Patent No. 3,054,914 granted Sept. 18, 1962, the temperature differential should be at least 350 F., preferably from 400 F. to 500 F.

The collector 12 in the embodiment shown in FIG- URE 2 of the drawings is supported by the left hand end (viewing FIGURE 2.) of cold wall 19. The opposite end of cold wall 19, as shown in FIGURE 2, is secured to the supporting disc. Left hand end of wall 19 has mounted thereon an annular plate 25 of electrically-conducting, high temperature-resistant material such as protected tantalum or molybdenum hereinabove disclosed. Plate 25 is maintained in the desired spaced relation relative to the integral extension 26 of collector 12 by spacers 27 of electrically-insulating refractory material. Any desired number of such spacers 2'7 can be used, preferably three equispaced circumferentially. In this manner the collector 12 is positioned relative to the emitter 11 "spaced from the emitter 11 by the space 13, the extent of which is controlled by the spacers 27.

Annular plate 25 is maintained electrically-insulated from the collector 12 by the insulatting spacers 27 and by the insulators 28 which are attached to the metal plates 29 and 30. These plates are made of suitable alloys such as copper-nickel alloy or other suitable material of construction having the desired co-efficient of expansion and contraction when subjected to temperature changes.

Insulators 28 may be of aluminum oxide or other suitable electrically-insulating material effecting electrical insulation of the annular plate 25 relative to the collector 12. The metal plates 29 and 30 are secured respectively as by brazing to the annular plate 25 and the collector, as shown in FIGURE 2.

Thet assembly of annular plate 25 and the integral extension 26 of the collector 12 are maintained in tight engagement with the above described insulating spacers 27 by clamps 31 substantially U-shaped as shown in FIGURE 2 of electrically-insulating ceramic or other electricallyinsulating material. The clamp shown in the drawings involves a substantial U-shaped member having a threaded opening through which the threaded bolt 32 (FIGURES 2 and 6) passes into an opening 33 in the collector 12. FIGURE 6 shows two such clamps at diametrically opposite points; any desired number of such clamps can, of course, be used.

The collector 12 is thus supported relative to the emitter 11 in spaced relation providing the inter-electrode space 13, which can have therein an ionizable vapor such as cesium or other such Vapor negating space charge, with the emitter 11 electrically-insulated relative to the collector 12 and with adequate provision for relative expansion and contraction due to differential temperatures to which the collector and emitter are subjected when heating up, cooling down or in operation.

A heat exchange plenum chamber 35 is positioned contiguous to the surface of the emitter 11 to be heated. This plenum chamber 35 communicates with the inlet end of the exhaust tube 15. An accelerating orifice plate 37 is positioned contiguous to this plenum chamber. One side (the left hand side viewing FIGURE .2) of the orifice plate 37 defines one wall of the plenum chamber 35, the opposite wall of which plenum chamber is defined by the heated surfaces of the emitter 11. Orifice plate 37 is cylindrical in shape and is supported at its periphery within the combustion chamber 14 and thus mounted therein by the liner 38. This liner and the orifice plate 37 are of high temperature-resistant, oxidation-resistant material, such, for example, silicon carbide preferably, or tantalum or molybdenum, provided with surface coatings such as those hereinabove disclosed which protect the surfaces against oxidation.

Orifice plate 37 has therein a multiplicity of small openings 39 passing therethrough, desirably evenly spaced. The one or two circular rows of orifices 39 adjacent the outer periphery of the accelerating orifice plate 37 extend in a longitudinal direction, i.e., their axes are substantially parallel with the longitudinal axis of the combustion cham ber. One or more inner rows of orifices 39' are inclined in a direction toward the center of the emitter 11. In this way when the products of combustion generated in combustion chamber 14 pass through the openings in accelerating orifice plate 37 a multiplicity of jets result in the plenum chamber which impinge on the surface of the emitter to be heated. Those jets formed upon passage of the combustion products through the openings 39 impinge at right angles to the surface of the emitter. Those jets formed by passage of the combustion products through openings 39' impinge at an angle to the surface of the emitter to be heated. The inclined openings 39 are disposed to provide jets which impinge on the surface of the emitter opposite the inlet to the exhaust tube 15. The total number of openings 39 and 39' and their spacing is such that jets are produced which impinge on substantially the entire area of the surface of the emitter to be heated.

The cross-sectional area of the jets are controlled by the cross-sectional area of the openings 39 and 39 in the accelerating orifice plate 37. The smaller the cross-sectional area of these openings the better, provided they are not so small that they will become clogged during operation by finely divided particles in the combustion products. For an emitter having a diameter of 1 /2 inches, 20 to 40 openings evenly spaced, each having a diameter of from 80 to 96 mils has been found effective, This data is, of course, given for exemplary purposes. It will be understood that an orifice plate can be used having any de sired number of openings which result in the formation of a multiplicity of closely spaced, small cross-sectional area jets flowing through the heat exchange plenum chamber 35 and impinging on the surface of the emitter to be heated so that substantially the entire area of this surface has these fine jets playing thereon, thus minimizing, if not completely preventing, retention of stagnant gas or a laminar boundary layer of gas on this surface.

As clearly shown in FIGURES 2, 3, 4 and 5 of the drawings, the fuel supply lines 17 extend through the annular chamber 16 and terminate at the inlet end of the combustion chamber 14 to supply fuel to the combustion chamber. In FIGURE 3, eight fuel supply lines 17 are shown but any desired number can be used. The discharge ends of these fuel supply lines are positioned, as best shown in FIGURE 4, directly above an annular plate or ring 41 which rests on the outer wall of the exhaust tube 15. FIGURE 4 is a view of the upper (relative to the showing of FIGURE 2) portion of the mechanism for effecting turbulent mixing of the fuel and oxygen-containing gas at the inlet to the combustion chamber 14.

Annular plate 41 has thereon a plurality of spaced baifies or vanes 42 which are angularly disposed relative to the longitudinal axis of the combustion chamber as clearly shown in FIGURE 4. A second concentric annular ring 43 is positioned just above the tops of the battles 42 and has thereon a plurality of battles or vanes 44 also angularly disposed but in a direction opposite that of the battles 42 on the lower ring- 41. The oxygen-containing gas, which can be air or oxygen enriched air, is supplied from any suitable source to the annular preheating chamber'16 where it flows in heat exchange relation with the products of combustion exiting through exaust tube 15. The oxygen-containing gas stream thus enters and flows through the spaces between the baffles 42 on the lower ring 41 and the bafiles 44 on the upper ring 43, which bafiles impart turbulent motion to the flowing oxygen-contaming gas stream as it enters the combustion chamber 14.

The fuel, preferably natural gas or other combustible medium, liquid or gas, is discharged by the tubes 17 in the area where turbulence of the oxygen-containing gas is effected. Thus'a turbulent mixture of fuel and oxygencontaining gas is produced which enters the combustion chamber 14 and burns therein. The proportion of fuel and oxygen-containing gas should be such as to obtain complete combustion with little or no excess of oxygencontaining gas. Combustion has been effected utilizing atmospheric air introduced into preheating chamber 16 and natural gas as the fuel to generate temperatures in excess of 2000 F. Using oxygen enriched air higher temperatures are obtained. Temperatures as high as 4500 F. can be obtained with air and natural gas in the equipment herein disclosed. These temperatures refer to the temperatures of the combustion products at the exit end of the combustion chamber.

The oxygen-containing gas is supplied at a pressure just above ambient. Desirably the pressure of the oxygencontaining gas is not more than about six inches of water. The fuel, e.g., natural gas, is supplied at a pressure slightly above the pressure of the oxygen-containing gas. In the operation of an electronic engine it is important that the power consumption for the supply of the fuel and the oxygen-containing gas be kept at a minimum. It is a feature of this invention that the fuel and oxygen-containing gas are supplied at relatively low pressures, say not exceeding about six inches of water for the oxygencontaining gas supply and a slightly higher pressure for the fuel gas supply, which higher pressure does not exceed the pressure at which natural gas, for example, is readily available, so that little power is required to provide the fuel and oxygen-containing gas supply to the thermionic engine. Obviously, the smaller the power requirements for the input of oxygen-containing gas and fuel to the combustion chamber, the larger the net power output of the thermionic engine.

The exhaust tube 15 which can be of silicon carbide or other suitable high temperature, heat-conducting material is provided at its exit end 47 with a supporting disc 48 which enables connection, if desired, of the exit end of the exhaust tube 15 to a waste heat boiler or other economizer for conserving residual heat in the combustion products. Exhaust tube 15 passes through a supporting disc 49 bolted at spaced points to the disc 23 by bolts 51 which pass through suitable spacers 52 positioned between discs 23 and 49. The fuel lines 17, it will be noted, are positioned in the space between these discs 23 and 49. Disc 49 has in its face spaced openings 52 through which air enters the annular chamber when air is used as the oxygen-containing gas to support combustion of the fluid fuel. Using oxygen enriched gas, such gas is supplied to the annular chamber 16 directly or, if desired, oxygen can be admitted to this chamber for admixture with the air flowing therethrough, the resultant mixture being preheated as it passes through the annular chamber 16 in indirect heat exchange with products of combustion fiowing through exhaust tube 15.

In FIGURE 2, 55 is the electrically-conducting lead communicating with the emitter, and 56 the lead communicating with the collector. Power or DC. current generated by the thermionic engine is withdrawn through these leads. Lead 55 communicates with the emitter 11 through the annular plate 25 which is electrically-insulated from the collector 12 by the spacers 27 and 28, and is an electrical communication with the emitter through the housing Walls 18 and 19, both secured to metal supporting disc 23.

In the operation of the thermionic engine of FIGURES l to 6, fuel, preferably natural gas, is supplied through the fuel lines 17, and the fuel is discharged in the area of turbulence effected by the bafiles 42, 44 of the preheated oxygen-containing gas flowing through the spaces between these battles. A turbulent mixture of fuel and oxygencontaining gas is thus produced and enters the combustion chamber 14. Ignition can be effected by igniting the combustion gas from the exit end of exhaust tube 15. The resultant fiame travels through the exhaust tube, plenum chamber and combustion chamber. The products of combustion thus produced in combustion chamber 14 are jetted through the orifices 39, 39 in the accelerating orifice plate 37 through the plenum chamber 35 into impingement with substantially the entire area of the emitter 11 to be heated. The direct impingement of the multiplicity of small jets over substantially this entire area of the emitter 11 to be heated results in elimination of stagnant gas and laminar boundary layer contiguous to the emitter surface to be heated with consequent efficient transfer of heat under high-heat flux densities from the combustion products to the emitter. The multiplicity of jets merge into a common stream which flows through the plenum chamber 35 and exits through the exhaust tube 15 giving up heat to the incoming oxygen-containing gas.

The arrangement of annular preheating chamber 16, combustion chamber 14, and plenum chamber 35 communicating with the exhaust tube 15 which is thus in heat exchange relation both with the combustion chamber 14 and the annular preheating chamber 15 results in high heat eificiency and high heat transfer to the emitter. The latter is accomplished by the jetting of the combustion products in a multiplicity of small jets in impingement with the surface of the emitter to be heated, which jets cover substantially the entire surface and are formed by the orifices 39, 39 in the accelerating orifice plate 37.

Operating as hereinabove disclosed with the oxygencontaining gas supplied at a pressure of just above atmospheric and below six inches of water, natural gas at aslightly higher pressure, and with the orifice openings dimensioned as hereinabove set forth for a 1 inch diameter emitter, jet velocities of about 350 feet per second are obtained. The accelerating orifice plate for any given installation should be designed to give jet velocities of at least 100 feet per second, preferably about 350 feet per second. The jet velocity is, of course, determined by the cross-sectional area of the orifice openings.

In the modification of FIGURE 7, a multiplicity of diodes 60 are arranged radially relative to a central annular combustion chamber 61. Each diode 60 comprises an emitter 62 spaced from a collector 63 having cooling fins 64. Since these diode constructions can be of the same type as disclosed above in connection with FIGURES l to 4, inclusive, further description thereof is believed unnecessary except to note that any desired number of them can be arranged in spaced relation within a housing 65 so that the cooling fins 64 are positioned contiguous to the housing 65 as shown in FIGURE 7, and the emitter 62 of each diode of the group is positioned contiguous to the combustion chamber 61.

Parts of FIGURE 7 which correspond with those of FIGURES 1 to 5, inclusive, are identified by the same reference characters.

In FIGURE 7, the combustion chamber 61 is supplied with fuel through the fuel inlets 66 and with oxygencontaining gas through annular space 75 and the ducts 67 in heat exchange relation with ducts 68 through which pass the products of combustion exciting from the exhaust chamber 69 which communicates with the plenum chamber 70. Mixing of the oxygen-containing gas and fuel takes place as these media are delivered to and flow through the vaned mixers M which produce turbulent mixtures of these media at the inlet ehd of the annular combustion chamber 61.

In the modification of FIGURE 7, the plenum chamber 70 is annular in shape and has wall 71 thereof contiguous to the surface of the emitter to be heated. Wall 71 has therein a plurality of orifices 72 arranged to jet the combustion products passing therethrough on the emitter surface to be heated. Theseorifices, as shown in FIG- URE 7, are arranged in groups, the groups being spaced from each other and each group being disposed opposite an emitter 62. The number of orifices in each group will, of course, depend on the emitter surface area; the num- 'ber should be so chosen as to provide jets of small diameter cross-sectional area impinging on substantially the entire area of the emitter surface to be heated as hereinabove disclosed inconnection with the description of the diode of FIGURES 1 to 6, inclusive.

The jets of combustion products after impinging on the emitter surfaces flow into a common stream which passes through the plenum chamber 70 into the inlet end 73 of the exhaust tube 69.

In FIGURE 7, 75 indicates insulation provided about the combustion chamber and the exhaust tubes for combustion prdoucts to conserve heat. As indicated, annular space 75 between the outer wall of the housing W and the layer of insulation 75 serves to supply oxygen-containing gas to the combustion chamber 61. A blower or fan (not shown) communicates with annular space 75 and the ducts 67 to supply the inlet ends thereof with air or other oxygen-containing gas.

Cesium reservoir tube C of each diode 60 communicates with a passageway C. This passageway C is communicably connected with the space 13 between the collector and the emitter through the annular space shown in FIGURE 7 surrounding the collector. Space 13 is evacuated through passageway C which, after evacuation has been completed, is sealed. Cesium reservoir tube C contains a glass capsule of liquid cesium which when tapped slightly is readily broken to release the cesium into the evacuated area, including the space 13 between the emitter and collector.

The operation of the construction of FIGURE 7 should be evident from the above description of the invention.

The structure of this figure differs primarily in that it involves simultaneous heating of a multiplicity of electronic engines or diodes rather than a single engine as in the case of FIGURES 1 to 5, inclusive.

It will be noted that the present invention provides a high temperature generating high intensity burner which operates efficiently with fossil fuels, with good fuel economy, which is safe, compact, durable and with its associated parts, including the material heated by the combus: tion products formed of a mass and size such that the units containing the burner are conveniently portable. In the operation of such burners, in accordance with this inventiomhigh temperatures are generated, with a minimum of extraneous heat loss, good fuel economy and safety.

This invention is not restricted to the present disclo sure, including the embodiments shown in the drawings, otherwise than as defined by the appended claims.

What is claimed is:'

1. A burner comprising in combination a longitudinally elongated combustion chamber having a fuel inlet end and an oppositely disposed heat transfer surface, said heat transfer surface comprising a material of good heat conductivity; an orifice member having a multiplicity of closely spaced orifice openings positioned close to said heat transfer surface with each of said orifice openings disposed to provide a jet of combustion products passing from said combustion chamber through said orifice openings onto said heat transfer surface; means for supplying said combustion chamber with fuel and with an oxygen containing gas to support combustion of said fuel at the end thereof remote from said heat transfer surface; means for passing said combustion products after the jetting thereof onto said heat transfer surface in indirect heat exchange relation with oxygen containing gas employed to support combustion of said fuel; and insulation surrounding the combustion chamber and means for passing combustion products to minimize loss of heat there from and from said combustion products flowing in indirect heat exchange relation with said oxygen-containing gas.

2. A burner comprising, in combination, a longitudinally elongated combustion chamber having a fuel inlet end and an oppositely disposed heat transfer surface, said heat transfer surface comprising a material of good heat conductivity; an orifice member having a multiplicity of closely spaced orifice openings positioned close to said heat transfer surface with each of said orifice openings disposed to provide a jet of combustion products passing from said combustion chamber through said orifice opening onto said heat transfer surface; means to supply fuel to said combustion chamber; means to supply an oxygen-containing gas to said combustion chamber to support combustion of said fuel, the products of combustion thus formed flowing through said combustion chamber through the orifice openings in said orifice member forming jets impinging on the heat transfer surface; means for passing the products of combustion from this heat transfer surface in heat exchange relation with the oxygencontaining gas supplied to said combustion chamber to preheat said oxygen-containing gas and insulation surrounding said combustion chamber, said means for passing the products of combustion and said means to supply an oxygen-containing gas to the combustion chamber to minimize heat losses from the burner.

3. A burner comprising, in combination, a surface to be heated, a combustion chamber housing having a central duct for discharge of products of combustion positioned with the end of the combustion chamber which communicates with the inlet to said central duct positioned adjacent the said surface to be heated, said combustion chamber having an annular chamber surrounding said central duct, means for passing oxygen-containing gas through said annular chamber to preheat the said oxygencontaining gas, means for introducing a fluid fuel in ad mixture with the preheated air to produce a turbulent mixture of fluid fuel and oxygen-containing gas at the inlet to said annular chamber, an orifice member having a multiplicity of small orifices therein positioned at the end of the combustion chamber adjacent the surface to be heated and arranged to jet the combustion products onto the said surface to be heated, the products of combustion thus jetted then flowing through said central duct, and insulation surrounding said combustion chamber.

4. A burner comprising, in combination, a cylindrical housing, a surface to be heated at one end of said cylindrical housing, an exhaust tube in said cylindrical housing having its axis coaxial with that of said housing and of a smaller diameter to provide a central duct with an annular space surrounding said central duct, the inlet to said central duct being positioned close to but spaced from said surface to be heated, means to supply an oxygencontaining gas to said annular space, baffies in said annular space through which the oxygen-containing gas flows to impart turbulent flow thereto, means to supply fluid fuel to said annular space in the vicinity of said baffles to produce a turbulent mixture of fluid fuel and oxygencontaining gas, and an orifice member spaced from said surface to be heated in the space between the inlet end 110 of said exhaust tube and said cylindrical housing having a multiplicity of orifices directed to jet the combustion products into impingement with substantially the entire area of one side of said surface to be heated to transfer the heat of the products of combustion efliciently and with high heat flux densities to said surface to be heated.

References Cited UNITED STATES PATENTS 664,683 12/1900 Schoettl et a1. 122467 731,300 6/1903 Holland 1581.5

741,485 10/1903 Green 122467 792,642 6/ 1905 Williams 1587.6 X 1,801,670 4/1931 Isley 110'-56 1,804,777 5/1931 Jerome 1221 15 2,147,803 2/1939 Steck. 2,838,042 6/1958 Chen 1587 X 3,212,554 10/1965 Blaha 158-7 X 3,243,612 3/1966 Lyczko 15899 FOREIGN PATENTS 779,669 7/ 1957 Great Britain.

JAMES W. WESTHAVER, Primary Examiner. 

1. A BURNER COMPRISING IN COMBINATION A LONGITUDINALLY ELONGATED COMBUSTION CHAMBER HAVING A FUEL INLET END AND AN OPPOSITELY DISPOSED HEAT TRANSFER SURFACE, SAID HEAT TRANSFER SURFACE COMPRISING A MATERIAL OF GOOD HEAT CONDUCTIVITY; AN ORIFICE MEMBER HAVING A MULTIPLICITY OF CLOSELY SPACED ORIFICE OPENING POSITIONED CLOSE TO SAID HEAT TRANSFER SURFACE WITH EACH OF SAID ORIFICE OPENINGS DISPOSED TO PROVIDE A JET OF COMBUSTION PRODUCTS PASSING FROM SAID COMBUSTION CHAMBER THROUGH SAID ORIFICE OPENINGS ONTO SAID HEAT TRANSFER SURFACE; MEANS FOR SUPPLYING SAID COMBUSTION CHAMBER WITH FUEL AND WITH AN OXYGEN CONTAINING GAS TO SUPPORT COMBUSTION OF SAID FUEL AT THE END THEREOF REMOTE FROM SAID HEAT TRANSFER SURFACE; MEANS FOR PASSING SAID COMBUSTION PRODUCTS AFTER THE JETTING THEREOF ONTO SAID HEAT TRANSFER SURFACE IN INDIRECT HEAT EXCHANGE RELATION WITH OXYGEN CONTAINING GAS EMPLOYED TO SUPPORT COMBUSTION OF SAID FUEL; AND INSULATION SURROUNDING THE COMBUSTION CHAMBER AND MEANS FOR PASSING COMBUSTION PRODUCTS TO MINIMIZE LOSS OF HEAT THEREFROM AND FROM SAID COMBUSTION PRODUCTS FLOWING IN INDIRECT HEAT EXCHANGE RELATION WITH SAID OXYGEN-CONTAINING GAS. 